Field of the Disclosure
The present disclosure relates to an apparatus for controlling an induction machine.
Discussion of the Related Art
In general, rotor position sensors such as an encoder and a resolver are useful for enhancing performance of a motor driving. However, these position sensors have disadvantages of being vulnerable to a vibration and increasing cost for the total system. Therefore, needs for the techniques for driving a motor without a position sensor are increasing, due to these problems.
The motor driving methods without a position sensor (sensorless) are mainly used in HVAC (Heating, Ventilation, Air-Condition) loads such as fans, pumps, and compressors, or up and down loads such as elevators and cranes, for the purpose of speed control.
In addition, the sensorless driving methods of an induction motor are mainly used for the purpose of torque control for the devices such as conveyors.
However, in a general sensorless torque control method, it is known that the driving performance in a low speed and low torque area is declined compared to the driving performance in a speed control method.